To make the quinoa chili: In a large pot with a lid, heat oil over medium-high heat. Add onion and sauté 5-7 minutes, or until translucent, fragrant, and beginning to brown. Add garlic and sauté additional 2-3 minutes.
Add in remaining ingredients except quinoa, masa harina, and salt. Stir to combine. Bring to a boil, reduce to a simmer, stir in quinoa, cover and simmer for 30 minutes, stirring occasionally.
After 30 minutes, quinoa should have "sprouted its tails." Stir in masa harina 1/4 cup at a time to thicken up to desired consistency. Add salt, to taste.
To serve, drizzle liberally with Cilantro Lime Cashew Sauce (see below) and garnish with green onion, cilantro, and pepitas.
To make the Cilantro Lime Cashew Sauce: Add cashews, oil, water, lime juice and garlic to the blender and puree until very smooth.
Add in cilantro and pulse until blended but specks of cilantro still remain. Add salt, to taste. Store in an airtight container in the refrigerator until ready to use.